This is a competitive renewal of the University of Pittsburgh Obesity/Nutrition Research Center (ONRC). The goal of this ONRC is to develop more effective interventions for the prevention and treatment of obesity. This focus is significant since there are 50 million Americans who are obese, and current efforts at treatment are only moderately successful. The University of Pittsburgh is uniquely qualified to focus on intervention research, since the Director, Dr. Rena R. Wing, is internationally known for her research on this topic. The Associate Director, Dr. David Kelley brings complementary expertise in the area of metabolism. The University of Pittsburgh currently has over 60-funded research projects related to obesity and nutrition. These projects are being executed by researchers in the Departments of Psychiatry, Epidemiology, Medicine, Pediatrics, Obstetrics and Gynecology, and Psychology. The goal of the ONRC is to promote multidisciplinary research between these investigators and to encourage young investigators to enter the field. Evidence that the ONRC is achieving these goals comes from new funding received as the Lifestyle Resource Core of the DPP, as one of two centers in the Health, Aging, and Body Composition Study, and the reorientation of a program project on preeclampsia to focus on lipids and obesity; in addition 9 out of 15 pilot feasibility grants funded before 5/96 have led to additional funding for obesity research. The goals of the ONRC are achieved through a speaker series, a pilot feasibility grant program, and five Core Facilities: An Administrative Core (with a statistical subcore), a Metabolic Body Composition, and Clinical Assessment Core, a Biochemistry and Genetics Core, a Behavior Core, and an Intervention Core. Each of these cores is designed to increase collaborative research and bring new investigators into the field through provision of shared resources and staff; consulting assistance; development of new methods; and providing training opportunities. The focus of the Pittsburgh ONRC on intervention research should complement that of other centers and promote scientific research on the critical issues of treatment and prevention.